Decoupled transverse flow metering gap and lip gap

ABSTRACT

The present invention provides a slot die that includes a flow passageway that includes a transverse flow-providing manifold, a flow metering section that provides a transverse flow metering gap, and an exit channel that includes an exit orifice. In accordance with the invention, the transverse flow metering gap may beneficially be selected independent of changing the gap or width of the exit office, using one or more normally non-adjustable die bodies.

FIELD OF THE INVENTION

This invention relates to a slot die for casting fluids, or for coatingfluids onto various substrates.

BACKGROUND OF THE INVENTION

It is known that the volumetric flow rate of a fluid passing through arectangular metering gap is governed by, and is inversely proportionalto, flow resistance, where the flow resistance is comprehended by theformula

${\Delta\; P} = \frac{12\eta\;{LQ}}{{WH}^{3}F_{p}}$where P is Pressure, η is the fluid viscosity, Q is the volumetric flowrate, W is the width of the flow channel transverse to the maindirection of fluid outflow, L is the length of the transverse meteringchannel in the main outflow direction, H is the transverse meteringchannel gap, and F_(p) is the geometric shape factor. It can beappreciated from this formula that volumetric flow rate is responsive toflow resistance and is particularly sensitive to the metering gap.

To provide regulation of the transverse mass flow distribution through aslot die, a transverse flow metering channel (commonly called a prelandchannel), is typically positioned between and in fluid communicationwith a transverse flow-providing manifold and an exit channel. Thetransverse flow metering channel provides regulation of the transversedistribution of a flow stream by regulating the resistance to flowthrough a combination of gap and gap length geometries defining thetransverse flow metering gap and channel in accordance with thegoverning principles of the preceding formula. Depending upon processobjectives, a transverse flow metering channel may be used to provide agenerally uniform, or a non-uniform, casting or coating thickness.

A conventional slot die as generally illustrated in FIG. 1, may includea body shim 1 disposed between two die bodies 2,3 to provide selectionof a lip gap complementary to the processability and application of theparticular fluid to be processed. A slot die flow passageway includes atransverse flow-providing manifold 4, a flow metering section 5 (prelandchannel) that provides a transverse flow metering gap, and an exitchannel that provides a metering function and that includes an exitorifice 6 (the lip gap). Metering of the fluid through the lip gap iscritical to the particular casting or coating process employed; and as aresult, there is a need to select and establish an appropriate lip gapbased on considerations including the particular fluid to be processedand/or the downstream process. To this end, a body shim may bebeneficially selected to provide a predetermined lip gap, and asillustrated, is usefully disposed between the two die bodies andgenerally parallel to the Z-axis of an X-Y-Z coordinate system (see FIG.5 for all three axes of the X-Y-Z coordinate system).

Without a body shim, the lip gap would be relatively smaller thanillustrated (compare for example, to the lip gap of the slot die of FIG.2). Body shims having a variety of thicknesses are available, and can besubstituted for one another, to select a variety of predetermined lipgaps. A series of body assembly bolts A (only one shown) fasten diebodies 2,3 together and extend through mechanical clearance holes C(only one shown) in die body 2. A body shim can be replaced bydisassembling the slot die to provide access to the body shim,substituting one body shim for another, and re-assembling the die bodiesback together.

Hypersensitivity of volumetric flow rate to metering gap changes in slotdie processes is known to be attributed to its inverse proportionalityto flow resistance, as supported by the foregoing formula. Asillustrated by U.S. Pat. No. 4,372,739 to Vetter, U.S. Pat. No.4,695,236 to Predohl et al, U.S. Pat. No. 4,708,618 to Reifenhauser etal, U.S. Pat. No. 5,066,435 to Lorenz et al, and U.S. Pat. No. 5,147,195to inventor Peter F. Cloeren, apparatus used for extruding thermoplasticresins may use a slidably adjustable restrictor bar to provide meteringgap adjustment. Mechanical clearance allows movement of a restrictorbar, by a bolt that passes through a die body.

It is typical to change the exit orifice width to accommodate differentproduct width requirements. Conventional external deckles are notsuitable for slot die casting or coating processes, due to the closeproximity of the die exit slot to the casting or coating surface,typically in the range of 50 to 3000 μm. Thus, a casting fluid orcoating fluid is generally delivered from a slot die in close proximityto a casting or coating surface. Nor are slot dies suitable forconventional internal deckles, as generally illustrated in Cloeren U.S.Pat. Nos. 5,451,357 and 5,505,609, due to the relatively small meteringgaps used. Accordingly, in a slot die, a deckle shim (see FIGS. 10 and11 for illustrative prior art deckle shims) may be conveniently disposedbetween die bodies 2,3 instead of body shim 1 (see FIG. 1) to establisha predetermined lip gap (in which case it functions in part as a bodyshim) and a predetermined exit orifice width.

However, with reference again to the slot die of FIG. 1, a problem withthe prior art use of a body shim or a deckle shim to establish apredetermined lip gap is that the shim also simultaneously changes thetransverse flow metering gap of flow metering section 5. As can beappreciated from the very small transverse flow metering gapscustomarily used and the resulting volumetric flow ratehypersensitivity, any change in the transverse flow metering gap canadversely affect the desired transverse metering of the fluid flowprovided by metering section 5. Different approaches such as a two stagepreland channel as exemplified by U.S. Pat. No. 5,256,052 issued toinventor Peter F. Cloeren, and a coat-hanger shaped preland channel,have been applied in the prior art slot die of FIG. 1 but found to besubject to volumetric flow rate hypersensitivity, and accordingly to beineffective in sufficiently regulating the transverse flow through flowmetering section 5 when a body shim or deckle shim of a differentthickness is selected to establish a different predetermined lip gap.

Furthermore, in slot die casting or coating processes, adjustment of thetransverse flow metering gap independent of changing the lip gap can bebeneficial or necessary to accommodate process changes such as differentflow rates, different fluid viscosities, and other process objectives.

With reference now to the slot die of FIG. 2, it is also known in theprior art to fit die bodies 2,3 with removably mounted lip inserts 7 toform exit orifice 6. Lip inserts are beneficial, for example, forgeneral wear and tear purposes. Although not shown in FIG. 2, it isrecognized that a lip shim can be inserted between a surface 8 of theremovably mounted lip insert and the respective die body surface toestablish the lip gap. However, a drawback for certain slot dieapplications, is a resulting interruption of the flow surface of theexit channel at the junction of the lip insert and the respective diebody.

With continued reference to the slot die of FIG. 2, it is known forcertain process applications to use an exit orifice in which one lipextends beyond the other lip. Die bodies 2,3 are normally non-adjustablerelative to one another as a result of being fastened together by aseries of body assembly bolts A (only one shown). However, looseningbody assembly bolts A allows positioning of die bodies 2,3 relative toone another. To also allow the relative positioning, it is known for diebody 2 to be provided with bolt clearance apertures D (only one shown),appropriately sized to provide for Z-axis relative movement of diebodies 2,3. It is also known for die body 3 to include a backingstructure B, and for a backing shim 9 of an appropriate thickness to beremovably disposed between backing structure B and a rear wall R of diebody 2. The backing structure may, as illustrated, be an integral partof die body 3, or may be removably attached. For clarity ofillustration, body bolt A is shown in a rearward position relative toclearance aperture D.

Accordingly, there continues to be a need for an improved slot andmethodology that provide for transverse flow metering gap adjustmentindependent of changing other flow channel metering gaps. Beneficially,an improved slot die would allow adjustment of the transverse flowmetering gap independent and apart from changing the lip gap.Beneficially, an improved slot die would also allow selecting adifferent lip gap by the use of body shims of different thicknesses orotherwise, independent and apart from changing the transverse flowmetering gap. Advantageously, an improved slot die would also allowselecting a different exit orifice width or dividing an outflowingstream into two or more streams by the use of deckle shims, independentand apart from changing the transverse flow metering gap.

SUMMARY OF THE INVENTION

The present invention is beneficially directed to a slot die having afunctionally decoupled transverse flow metering gap and lip gap. Aninventive slot die may be used for casting fluids, or for coating fluidsonto various substrates. These fluids may be slurries, solutions,suspensions of particles or colloids in fluids, emulsions, polymermelts, and so forth. Slot die process requirements and fluid propertiesare generally of a character such that micro metering gap changespropagate relatively macro changes to the transverse mass flowdistribution. The present invention further includes methodology foradjusting a transverse flow metering gap of a slot die without changingthe lip gap.

In accordance with the present invention, there is provided an improvedslot die that includes a flow passageway that includes a transverseflow-providing manifold, a flow metering section including a meteringgap that provides for transverse flow metering of a fluid passingtherethrough, and that is in fluid communication with the transverseflow-providing manifold and an exit channel that includes an exitorifice (the lip gap) of the flow passageway. In accordance with theinvention, an improved slot die further includes a first die body, asecond die body having a metering face, and a third die body having anopposing metering face that beneficially cooperates with the meteringface of the second die body to form the transverse flow meteringsection.

Unlike an adjustable restrictor bar, the die bodies are normallynon-adjustable. The die bodies are normally non-adjustable relative toone another as a result of being fastened together by a series of bodyassembly bolts. However, after the body assembly bolts are loosened, thedie bodies are positionable relative to one another. Subsequent todesired positioning, the die bodies are again fastened together.

In a first embodiment of the invention, the second die body or the thirddie body, when positionable, has an axis of movement that defines aZ-axis of an X-Y-Z coordinate system. In this embodiment, the meteringgap of the transverse flow metering section is advantageously adjustableby movement of the second die body or third die body along the Z-axis,and is beneficially adjustable independent of changing the lip gap. Ifdesired, the second die body and the third die body may be independentlypositioned to form the transverse flow metering gap.

Beneficially, the transverse flow metering gap is predetermined, and maybe obtained by using a backing shim or the equivalent of an appropriatethickness or extent, for precision positioning of a positionable diebody in a Z-axis direction. Alternatively or in combination, to obtain apredetermined transverse flow metering gap, the second die body or thirddie body may be exchanged for a different die body of, for example,different Z-axis extent, or having different metering face geometry.

In a second embodiment of the invention, the second die body, whenpositionable, has an axis of movement along the Y-axis of the X-Y-Zcoordinate system. In this embodiment, the metering gap of thetransverse flow metering section is advantageously adjustable bymovement of the second die body along the Y-axis, and the metering gapmay be adjusted independent of changing the lip gap.

As before, the transverse flow metering gap is advantageouslypredetermined, but in this embodiment, an inventive slot diebeneficially includes a body shim to provide for adjusting thetransverse flow metering gap, and positioning of the second die body ina Y-axis direction may be accomplished by changing the location of abody shim after appropriately disassembling the slot die. If desired, acombination of body shims may be used. Furthermore, if desired, acombination of body shims may be used to also change the lip gap.Subsequent to desired positioning, the slot die is re-assembled.

Advantageously, the flow metering section, which provides the transverseflow metering gap, is disposed at an angle α ranging from about 20 to160°, with respect to the Z-axis, which as explained, in a firstembodiment of the invention is the axis of movement of a positionabledie body. Preferably, the angle α is in the range of about 30 to 60°, orof about 150° to 120°, with respect to the Z-axis. An angle α of about45° may provide the most suitable balance between fluid flowrequirements, operability functionality and mechanical designrequirements.

As mentioned, an inventive slot die may include a body shim. A body shimor a combination of body shims may be structurally disposed between thesecond die body and the first die body, and/or between the second diebody and the third die body. A body shim is normally non-adjustable whenan inventive slot die is fastened together by a series of body assemblybolts, but after the body assembly bolts are loosened, a body shim maybe positionable in a Z-axis direction. Beneficially in a firstembodiment of the invention, a body shim, when positionable, may bepositionable by movement consistent with Z-axis positioning of apositionable die body. To this beneficial end, an inventive slot die mayfurther include alignment pins or fasteners that extend through the bodyshim.

Advantageously, an inventive slot die may include a deckle shim. Adeckle shim is suitably disposed in structural contact with the firstdie body. Conveniently, a deckle shim may be maintained stationary in aZ-axis direction.

The first and second embodiments of the invention are not mutuallyexclusive. To the contrary, the second inventive embodiment may alsoutilize Z-axis positioning, and the first inventive embodiment may alsoutilize Y-axis positioning.

If desired for regulation of the lip gap, an inventive slot die mayinclude removably mounted lip inserts with or without lip shimsdepending upon process requirements, or an adjustable lip. After thebody assembly bolts are loosened, if it is desired for one lip to bepositioned beyond the other lip, the first and third die bodies arepositionable along the Z-axis relative to one another.

The exit channel of an inventive slot die may extend generally along theZ-axis, and fluid flow through the exit channel may be generally in aforward Z-axis direction. Beneficially, the body assembly bolts extendthrough the first die body and are in axial alignment with the Y-axis ofthe X-Y-Z coordinate system.

Additional advantages and beneficial features of the present inventionare set forth in the drawing and detailed description, and in part willbecome apparent to those skilled in the art upon examination of thedrawing and detailed description or may be learned by practice of theinvention. In the drawing and detailed description, there are shown andessentially described only preferred embodiments of this invention,simply by way of illustration of the best mode contemplated of carryingout this invention. As will be realized, this invention is capable ofother and different embodiments, and its several details are capable ofmodification in various respects, all without departing from theinvention. Accordingly, the drawing and the detailed description are tobe regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference now is made to the accompanying drawing which forms a part ofthe specification of the present invention, and which beginning withFIG. 3, illustrates preferred slot dies in accordance with the presentinvention. For clarity of understanding, certain features areexaggerated in relative size or have been omitted from certain Figures.

FIG. 1 is a cross-sectional view of a prior art slot die that includes abody shim, and that shows the Y-axis and Z-axis of an X-Y-Z coordinatesystem;

FIG. 2 is a cross-sectional view of another prior art slot die without abody shim, but that illustratively includes an optional combination ofremovably mounted lip inserts, and bolt clearance apertures (only oneshown) and a backing shim for positioning of one lip beyond the otherlip;

FIGS. 3 and 4 are simplified cross-sectional views taken at thecenter-line of a first embodiment of a slot die in accordance with thepresent invention, that includes a body shim and an especiallyexaggerated exit channel and bolt clearance apertures (only one shown),and which views together illustrate selectable movement of a die body ina Z-axis direction from a relatively rearward position that provides arelatively greater predetermined transverse flow metering gap, to arelatively forward position that provides a relatively smallerpredetermined transverse flow metering gap;

FIG. 5 is a simplified partial perspective view of a variation of theinventive slot die of FIG. 3, which includes a cross-sectional viewtaken at the center-line, which illustrates a die body positioned in aforward Z-axis direction using a plurality of removably disposed backingshims, and shows all three axes of the X-Y-Z coordinate system, andwhich illustrates the use of alignment pins and clearance apertures(only one clearance aperture and alignment pin shown) to allowpositioning of a body shim consistent with the Z-axis movement of thedie body;

FIG. 6 is a simplified cross-sectional view taken at the center-line ofanother variation of the inventive slot die of FIG. 3 (the clearanceaperture and alignment pin details shown in FIG. 5, here omitted as inFIGS. 3 and 4), which illustrates an obtuse angle of arrangement of atransverse flow metering section with respect to the Z-axis, and a diebody positioned in a forward Z-axis direction using a removably disposedbacking shim and an integral backing structure;

FIGS. 7 and 9 are simplified cross-sectional views taken at thecenter-line of a variation of the inventive slot die of FIG. 5, thatincludes a deckle shim instead of a body shim, and which views togetherillustrate selectable movement of a die body in a Z-axis direction froma relatively rearward position that provides a relatively greaterpredetermined transverse flow metering gap, to a relatively forwardposition that provides a relatively smaller predetermined fixedtransverse flow metering gap, using a backing shim, and which illustratethe use of fasteners (only one shown) to maintain the deckle shimstationary, and of clearance apertures (only one shown) to allow theZ-axis die body movement;

FIG. 8 is a partial perspective view of, in particular, the forward faceof a die body of FIGS. 7 and 9;

FIG. 10 is a simplified perspective view of the inventive slot die ofFIG. 9 (end plates and certain other details omitted), which shows theupper die body in phantom, a plurality of removably disposed backingshims for predetermined positioning in a forward Z-axis direction, andwhich shows further details of the deckle shim;

FIG. 11 is a simplified perspective view like that of FIG. 10 of avariation of the inventive slot die of FIG. 7, which shows a singlebacking member, and a deckle shim for dividing a flow stream into twosubstreams; and

FIGS. 12 and 13 are simplified cross-sectional views taken at thecenter-line of a second embodiment of a slot die in accordance with thepresent invention, that includes a body shim and an especiallyexaggerated exit channel, and which views together illustrate selectablemovement of a die body upward along the Y-axis to provide a relativelygreater predetermined transverse flow metering gap, or downward alongthe Y-axis to provide a relatively smaller predetermined transverse flowmetering gap, depending upon the original location of a body shim.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, there is provided an improvedslot die and related inventive methodology. Fluids processed by a slotdie in accordance with the present invention, may be slurries,solutions, suspensions of particles or colloids in fluids, emulsions,polymer melts and so forth. By way of example, these fluids may includecarriers such as ketones including methyl ethyl ketone, acetone, methylisobutyl ketone and cyclohexanone, methylene chloride, alcohols such asmethanol, ethanol, n-propranol, isopropanol and isobutanol, cyclohexane,acetates including ethylacetate and n-butylacetate, glycols includingethylene glycol and propylene glycol, heptane, dioxane, toluene, xylene,tetrahydrofuran, and water. Organic or inorganic compositionsprocessable using a slot die process, including low molecular weightpolymers, can be processed using an inventive slot die.

Beneficially, an inventive slot die and related inventive methodologyprovide for adjustment of a transverse flow metering gap independent ofchanging the lip gap. The metering gaps employed in slot die processesare generally of a size such that micro metering gap changes propagaterelatively macro changes to the transverse mass flow distribution. Slotdie process requirements and fluid properties dictate that thetransverse flow metering gap is generally in the range of about 50μm-1000 μm, and the lip gap is generally in range of about 50 μm-500 μm.

In the description of the invention, relative terms such as “upper”,“lower”, “forward”, “rearward”, “upward”, “rear,” and the like have beenused particularly with reference to the drawing to assist understanding.

Referring to a first embodiment of an inventive slot die and beginningwith FIGS. 3 and 4, a preferred single cavity slot die 10 in accordancewith the present invention, includes an upper die body 12, and a lowerdie body 14 and a die body 16 that cooperatively provide for selectionof a transverse flow metering gap H (shown in FIG. 3) of a transverseflow metering section 34. Preferred slot die 10 further includes a flowpassageway 30, which includes transverse flow metering section 34, and adownstream exit orifice 40 (the lip gap).

Die bodies 12,14,16 are normally non-adjustable relative to one anotheras a result of being fastened together by a series of body assemblybolts 36 (only one shown in FIGS. 3 and 4). However, the body assemblybolts are loosened sufficiently so that die bodies 12,14,16 arepositionable relative to one another. Subsequent to desired positioning,the die bodies are again fastened together to provide for fluidprocessing. When die bodies 12,14,16 are fastened together, there is nomechanical clearance to provide for the relative positioning.Accordingly, unlike a restrictor bar, die body 16 functions as a bearingmember. By the term “bearing member” is meant, for purposes of thisinvention, a mechanical member that supports another mechanical member.

Beneficially, die body 16, when positionable, has an axis of relativemovement that defines a Z-axis of an X-Y-Z coordinate system (shown inentirety in FIGS. 5 and 10), and that provides for selection oftransverse flow metering gap H. Likewise, lower die body 14, whenpositionable, has an axis of relative movement that defines a Z-axis ofan X-Y-Z coordinate system (Z-axis movement of die body 14 is not shownin the drawing), and that provides for selection of transverse flowmetering gap H. If desired, die body 16 and lower die body 14, whenpositionable, may be independently positioned to form transverse flowmetering gap H.

Advantageously, die body 16 includes a generally planar upper surface 26and a generally planar lower surface 28, and is located between agenerally planar surface 18 of upper die body 12 and a generally planarsurface 20 of lower die body 14. As illustrated, surface 20 may be anundercut rear portion 24 of lower die body 14.

Beneficially, the body assembly bolts extend through body bolt clearanceholes 37 in die body 12, and through body bolt clearance holes 39 in diebody 16 (only one of clearance holes 37,39 shown in FIG. 3), and arethreaded into lower die body 14. When an inventive slot die includes abody shim 90, the body assembly bolts extend through body bolt clearanceholes 38 in the body shim. As indicated in FIGS. 3 and 4, body boltclearance holes 39,38 in Z-axis positionable die body 16 and body shim90 are appropriately sized to provide for Z-axis movement of die body 16and/or 14 to form transverse flow metering gap H, and to provide forappropriate Z-axis movement of the body shim. To assist understanding,body bolt clearance holes 39,38 are shown exaggerated in size relativeto body bolt clearance holes 37. For clarity of the drawing, thesefeatures have been omitted from FIGS. 5, 6 and 8 to 11.

Body bolt 36 is shown in FIG. 3 in a forward position relative toclearance holes 38,39, and in FIG. 4 in a rearward position relative toclearance holes 38,39. Forward Z-axis positioning of die body 16 orrearward Z-axis positioning of lower die body 14 to select a relativelysmaller transverse flow metering gap than gap H of FIG. 3, results inrearward positioning of the body assembly bolts relative to body boltclearance holes 39 in die body 16. Continuing with respect to FIG. 4,forward Z-axis positioning of die body 16 also beneficially results inforward Z-axis positioning of the body shim, and accordingly alsoresults in rearward positioning of the body assembly bolts relative tobody shim clearance holes 38.

Flow passageway 30 includes a manifold 32 to facilitate transverse flowof a fluid across the width thereof (that is, along the X-axis of theX-Y-Z coordinate system), flow metering section 34 that providestransverse flow metering gap H and that is in fluid communication withmanifold 32 to regulate the incremental transverse distribution of thefluid mass across the width thereof, and an exit channel 42 thatincludes final orifice 40 (the lip gap), which is the exit orifice ofthe flow passageway. The exit channel provides a flow resistancefunction. The two elongated arrows in flow passageway 30 show thegeneral direction of fluid flow through slot die 10, including the mainfluid outflow direction.

As shown, the exit channel and the lip gap may be provided by opposingsurfaces 18,22 of die bodies 12,14. If desired and with reference to thedescription of the slot die of FIG. 2, a slot die in accordance with theinvention, may include removably mounted lip inserts and, depending uponthe particular processing requirements, lip shims to establish apredetermined lip gap. Furthermore, the lip gap may be provided by anadjustable lip responsive to conventional adjustment means. After thebody assembly bolts are loosened, if it is desired for one lip to bepositioned beyond the other lip (not shown except in prior art FIG. 2),die bodies 12, 14 are positionable along the Z-axis relative to oneanother.

With continued reference to FIG. 3 in particular, die body 16 has ametering face 50 that beneficially cooperates with an opposing meteringface 52 of lower die body 14 to form transverse flow metering section34, and to provide transverse flow metering gap H. With particularreference to FIG. 4, flow metering section 34 has a length L in the mainoutflow direction. As shown, length L may be less than the length ofmetering face 50. Alternatively, as indicated in FIG. 6, flow meteringsection 34 may have a length that generally corresponds to the length ofmetering face 50. In any event, flow metering section 34 terminates atexit channel 42.

As illustrated in FIGS. 3, 4 and 6, metering face 50 and opposingmetering face 52 may be generally planar. However, the particulargeometric shape to be used for a metering face of a transverse flowmetering section in accordance with the present invention is governed byfluid flow requirements and process objectives. For example, asillustrated by a variation of inventive slot die 10 shown in FIG. 5, andby the variations of the inventive slot die of FIG. 5 shown in FIGS. 7to 11, and as described in further detail later, the transverse flowmetering section may advantageously include a primary metering stage,and a secondary metering stage that has a relatively larger transverseflow metering gap than the primary metering stage.

With respect to the variations of slot die 10 shown in FIGS. 5 to 11,for sake of brevity of the description of the invention, identicalreference numerals have been used in FIGS. 5 to 11 to indicate likeparts of slot die 10 of FIG. 3. Similarly, with respect to thedescription of a second embodiment of an inventive slot die, for sake ofbrevity of the description, identical reference numerals have been usedin FIGS. 12 and 13 to indicate like parts of slot die 10 of FIGS. 3 and7.

The slot die shown in FIG. 3 differs from the slot die shown FIG. 4 inthat, for sake of illustration, different backing structures 60,61 areused. Simplified FIG. 5 shows some structural details omitted fromsimplified FIGS. 3, 4 and 6: one alignment pin 91 of a plurality ofalignment pins, one clearance aperture 92 of a plurality of clearanceapertures in die body 12, and one snugly fitting aperture 93 of aplurality of such apertures in body shim 90.

Advantageously in accordance with a first embodiment of the invention,after the body assembly bolts are loosened, transverse flow metering gapH (shown in FIGS. 3 and 6) is adjustable by precise selectablepositioning of metering face 50 of die body 16 in a Z-axis directionrelative to opposing metering face 52 of die body 14. Alternatively, orin combination, lower die body 14 and metering face 52 thereof arepositionable along the Z-axis relative to die body 16 for selection oftransverse flow metering gap H. Beneficially, adjustment of thetransverse flow metering gap in this way does not change or otherwisealter the lip gap.

Length L of transverse flow metering section (or channel) 34 is selectedas required to accommodate the desired fluid flow processing objectives.Related to selecting length L, flow metering section 34 is arranged atan appropriate angle α relative to the Z-axis, which in a firstinventive embodiment is the axis of movement of die body 16 and die body14. Any suitable angle α may be employed consistent with the fluidprocessing objectives. Angle α may be an acute angle as illustrated inFIG. 3, a right angle, or an obtuse angle as illustrated in FIG. 6.Advantageously, flow metering section 34 is arranged at an angle αranging from about 20° to 160°, relative to the Z-axis.

With respect to Z-axis positioning of die body 16 or 14, compared to anangle α of 60° or 120°, an angle α of 30° or 150° provides relativelygreater adjustment precision of the transverse flow metering gap and arelatively longer forward face of die body 16 and hence a relativelylonger metering section length. However, with respect to Y-axispositioning of die body 16 (which is later described in detail withreference to FIGS. 12 and 13), compared to an angle α of 30° or 150°, anangle α of 60° or 120° provides relatively greater adjustment precisionof the transverse flow metering gap. Angle α is preferably an angle inthe range of about 30° to 60° or of about 150° to 120°. Angle α isappropriately selected to provide the most suitable balance of fluidflow processing requirements, mechanical design integrity and operatingfunctionality of the slot die.

With respect to Z-axis positioning of die body 16 or 14, an acute angleα of 45° (illustrated in FIG. 3) or an obtuse angle α of 135°(illustrated in FIG. 6) results in adjustment of the transverse flowmetering gap by 0.7 units for each 1.0 unit of Z-axis movement of diebody 16 or die body 14. A preferred balance between adjustment precisionand metering section length of flow metering section 34, will typicallybe provided when angle α is selected from the group consisting of arange of about 40° to 50°, and a range of about 140° to 130°. An angle αof about 45° will typically provide the most accommodating balancebetween fluid flow requirements, operability requirements, andmechanical design requirements.

With reference to FIGS. 5 and 7-11, an alternative geometric shape tometering face 50 of die body 16 is shown, and can best be seen in FIG.8. Alternative metering face 51 provides a two stage flow meteringsection 34 defined by a length L′ (shown in FIG. 8). With particularreference to FIGS. 7, 8, and 10, two stage flow metering section 34includes a primary metering stage 82 having a gap M (shown in FIG. 7)and a secondary metering stage 86 having a gap N (shown in FIG. 10). GapM is a relatively smaller metering gap than the gap of the secondarymetering stage, and is the primary flow restricting gap. Length L′ isconstant from side to side of flow metering section 34, and the lengthsof the two stages are inverse to one another. The two stages areprovided by a raised surface 80 and an undercut surface 84 of face 51 asdefined by length L′. A transition surface 88 is located betweensurfaces 80,84. For further details of two stage flow metering,reference is made to the pertinent portions of previously cited U.S.Pat. No. 5,256,052, which portions are hereby incorporated herein byreference.

As illustrated, raised surface 80 may be generally triangularly shaped.Surfaces 80,84 may be generally planar, generally arcuate along theX-axis, or be provided with any appropriate metering face shape alongthe X-axis consistent with fluid processing objectives or requirements.A multi-stage transverse flow metering section may be defined bymetering face 52 of die body 14, if desired.

Referring again to Z-axis positioning of die body 16 or 14 and selectingangle α, it may be appropriate for angle α to be substantially less thanabout 45°, for example about 30°, to provide additional forward facelength compared to angle α of about 45°, and thus may benefit fluid flowrequirements. Also to be considered is that because the metering sectionlength also depends on the thickness (that is, the Y-axis dimension) ofdie body 16 in that a relatively greater thickness provides for arelatively longer metering section length, an angle α of about 45° inthe case of die body 16 of relatively greater thickness, may provide themost accommodating design balance.

An inventive slot die may include a variety of backing structures,several of which are illustrated in the drawing by backing structures60,61,62. With reference to FIGS. 3 and 7, removably mounted backingstructure 60 is provided with an undercut area 64 that allows die body16 to be selectably positioned in a rearward Z-axis direction, and forflow metering section 34 to be provided with a predetermined transverseflow metering gap H (shown in FIG. 3), or with a predeterminedtransverse flow metering gap M (shown in FIG. 7), of relatively greatersize. With reference to FIG. 6, backing structure 62 integral to diebody 14, is provided with a backing face 65. With reference to FIG. 4,removably mounted backing structure 61 includes a wall portion 66 thatextends forward along the Z-axis for selectably positioning die body 16in a forward Z-axis direction, and for flow metering section 34 to beprovided with an alternative predetermined transverse flow metering gapof relatively smaller size. Conveniently, undercut area 64, backing face65, and wall 66 may be generally planar. Furthermore, as can best beseen from FIG. 10, a backing structure may conveniently be generallycoextensive in width to the width of a Z-axis positionable die body.

Backing structure 60 or 61 may be removably attached by fasteners (notshown) to a rear wall 56 of die body 14, or if desired, removablyattached to a rear wall 58 of die body 12 (attachment to rear wall 58 ofdie body 12 not shown). Alternatively, a backing structure may beintegral to die body 12. Regardless of the attachment location of abacking structure, Z-axis positioning of die body 16 and/or 14 forpositioning metering faces 50,52 relative to one another provides aselectable gap H of transverse flow metering section 34 separate andapart from changing the lip exit gap.

A backing structure with an undercut area of more or less depth alongthe Z-axis may be selected as desired. Likewise a backing structure witha forwardly extending wall portion of greater or lesser extent along theZ-axis, may be selected as desired. If desired, the functional face of abacking structure may lack an undercut area or a forwardly extendingwall portion.

Instead of a backing structure with a forwardly extending wall portion,a backing shim 68 of a selected generally uniform thickness may be usedin combination with a backing structure provided with an undercut areaor a backing face, for Z-axis positioning of die body 16 and/or 14 (seeFIGS. 6 and 11), and for flow metering section 34 to be provided with apredetermined transverse flow metering gap of relatively smaller sizethan without the backing shim. As indicated in FIG. 11, a backing shimmay be generally coextensive in width to the width of the die body to bepositioned along the Z-axis.

Alternatively, as illustrated in FIGS. 5 and 10, a plurality of backingshims 68 of a common)thickness may be spaced apart across the width ofthe die body to be positioned along the Z-axis. A greater or smallernumber of backing shims than illustrated may be used, with differentpositioning than illustrated.

Depending upon fluid processing objectives or requirements, die body 16of an inventive slot die, may be subjected to bending by the use ofrelatively centrally positioned backing shims of greater thickness incombination with relatively thinner shims positioned proximate to theends of the die body causing metering face 50 to be generally arcuatealong the X-axis, or if desired, may be subjected to an alternativepositioning of the backing shims to produce an alternative arcuate shapealong the X-axis of metering face 50. Other positioning of a pluralityof shims of different thicknesses may be used to change the meteringface shape along the X-axis, consistent with fluid processing objectivesor requirements. Transverse flow metering section 34 of a slot die inaccordance with the present invention, may be designed or adjusted toprovide a predetermined uniform or non-uniform casting or coatingthickness.

In the drawing, backing shims 68 are illustrated as extending upwardlyfrom a backing structure and angled away from the rear wall of aninventive slot die. However, neither feature is necessary.

With particular reference to slot die 10 of FIGS. 3 to 5, 7, and 9 to11, positioning of die body 16 or die body 14 in a Z-axis direction foradjustment of the transverse flow metering gap may be generallyfacilitated by cessation of fluid flow through the slot die, followed byloosening body assembly bolts 36 (one shown in FIGS. 3, 4 and 7;otherwise, as previously pointed out, bolts 36 omitted for clarity).Loosening or removing backing member fasteners (not shown) may befollowed by, for example, removing any existing backing shim(s) 68 orbacking member 61, as appropriate; and inserting or substituting backingshim(s) 68 of different appropriate thickness; or attaching a substitutebacking member 61 of an appropriate different extent along the Z-axis.After the backing member fasteners are tightened, the slot die issuitably fastened together by the body assembly bolts, followed byresuming fluid flow through the slot die.

Alternatively or in combination, after appropriately withdrawing thebody assembly bolts, die body 14 or 16 may be exchanged for a differentdie body, for example, having an alternative metering face and/or ofdifferent extent along the Z-axis. As previously described, the bodyassembly bolts will be sufficiently loosened to allow change to therelative Z-axis positioning of die bodies 12,14,16.

Accordingly, by use of an appropriate backing structure, with or withouta backing shim or shims as appropriate, a predetermined transverse flowmetering gap is obtained in an inventive first embodiment, with positiveincremental adjustment by Z-axis movement of die body 16 from arelatively rearward position to a relatively forward position, or Z-axismovement of die body 14 from a relatively forward position to arelatively rearward position, or with negative incremental adjustment byZ-axis movement of die body 16 from a relatively forward position to arelatively rearward position, or Z-axis movement of die body 14 from arelatively rearward position to a relatively forward position.

With continued reference to a first embodiment of the invention and inparticular to FIGS. 3 to 6, to provide for selection of the lip gap bythe use of body shims of different thicknesses, independent and apartfrom changing the transverse flow metering gap, a slot die in accordancewith the invention may include a body shim 90. Body shim 90 is suitablydisposed in structural contact with load bearing die body 16.Conveniently, the body shim may be disposed between die body 12 and diebody 16, and, when positionable, beneficially is positionable in aZ-axis direction by movement consistent with Z-axis positioning of diebody 16.

With reference to FIG. 5, conveniently, for Z-axis positioning of bodyshim 90 consistent with Z-axis positioning of die body 16, alignmentpins 91 (only one shown) may extend from die body 16 into receivingapertures 92 (only one shown) in die body 12, through snugly fittingapertures 93 (only one shown) in the body shim. Beneficially, asillustrated, receiving apertures 92 are appropriately sized to provideclearance for movement of the alignment pins, consistent with Z-axispositioning of die body 16. Although not shown, a plurality of alignmentpins and corresponding body shim apertures and receiving (or clearance)apertures in die body 12 may extend along the X-axis for this purpose.The shape of the clearance apertures, whether circular, rectangular,square or otherwise, is of no significance.

Alternatively, fasteners may extend through the body shim and may bethreaded into die body 16 to secure the body shim to die body 16. Inthis variation, die body 12 may be provided with clearance aperturessimilar to the clearance apertures of FIG. 5, for movement of fastenerheads in a Z-axis direction consistent with Z-axis positioning of diebody 16.

Referring again to FIGS. 7 and 9-11, a slot die in accordance with theinvention may include a deckle shim to provide for selection of the lipgap by the use of deckle shims of different thicknesses, and to providefor selection of the exit orifice width or dividing an outflowing streaminto two or more streams, independent and apart from changing thetransverse flow metering gap. As best understood from FIGS. 10 and 11,illustrative deckle shims 70, 72 include a least one leg 74, 76,respectively, that extends to the exit orifice.

A deckle shim is conveniently disposed generally parallel to the Z-axis,and suitably disposed in structural contact with die body 12.Conveniently, the deckle shim may be disposed in part between die body12 and die body 16, and in part between die bodies 12 and 14, toestablish a predetermined lip gap (in which case it functions in part asa body shim) and a predetermined metering orifice width.

Conveniently, a deckle shim may be maintained stationary relative to diebody 12. With reference to FIGS. 7 and 9 to 11, and to die body 16thereof, to maintain a deckle shim stationary relative to die body 12,the deckle shim may be secured to die body 12 using fasteners 95 (onlyone shown in FIGS. 7 and 9) having heads 96 (only one shown in FIGS. 7and 9) that extend into clearance apertures 97 (only one shown in FIGS.7 and 9) in die body 16. Beneficially, as illustrated, the clearanceapertures in die body 16 are appropriately sized to provide clearancefor Z-axis positioning of die body 16 without interference from thefastener heads. The fasteners extend through apertures 98 (only oneshown in FIGS. 7 and 9) in the deckle shim and are threaded into diebody 12. As indicated in FIGS. 10 and 11, a plurality of fasteners andcorresponding deckle shim apertures and clearance apertures in die body16 may extend along the X-axis for this purpose. The shape of clearanceapertures 97, whether circular, rectangular, square or otherwise, is ofno significance.

Illustrative deckle shims include deckle shim 70 of FIGS. 7, 9 and 10,and deckle shim 72 of FIG. 11. As illustrated in FIG. 11, a deckle shimcommonly referred to as a rake type deckle, may further include at leastone leg 78 to divide fluid outflow into two or more flow streams. Raketype deckles are employed in applications such as stripe coating. Otherdeckle shim constructions may be selected as desired or appropriate. Theslot die of FIG. 10 also differs from the slot die of FIG. 11 in the useof a plurality of backing shims, instead of a single backing shim.

Referring now to a second embodiment of the invention and specificallyto the inventive slot die of FIGS. 12 and 13, slot die 110 beneficiallyincludes body shim 90 or 90′, which are of the same thickness. Aspreviously explained, for sake of brevity of the description, identicalreference numerals are used in FIGS. 12 and 13 to indicate like parts ofslot die 10 of FIGS. 3 and 7. Slot die 110 includes body assembly bolts36 (one shown in each Figure), body bolt clearance holes 37 (one shownin each Figure) in die body 12, body bolt clearance holes 38 (one shownin each Figure) in shim 90 or 90′, and body bolt clearance holes 39 (oneshown in each Figure) in die body 16.

Beneficially, body shim 90 or 90′ is suitably disposed in structuralcontact with load bearing die body 16. The body shim may be disposedbetween die body 12 and die body 16 (FIG. 12), or between die body 16and die body 14 (FIG. 13), given that either location provides anidentical predetermined lip gap. Changing the location of a body shimincludes disassembling an inventive slot die to provide access to thebody shim and die body 16, and re-assembling the slot die to provide forfluid processing.

When angle α is an acute angle as shown in FIGS. 12 and 13, changing thelocation of a body shim from a location between die body 12 and die body16 (shown in FIG. 12) to a location between die body 16 and die body 14(shown in FIG. 13) moves die body 16 upward along the Y-axis andincreases metering gap H (shown in FIG. 12) of transverse flow meteringsection 34. Length L (shown in FIG. 13), which corresponds to the lengthof flow metering section 34, is decreased. Conversely, reversing thelocation of a body shim moves die body 16 downward along the Y-axis andreduces metering gap H of transverse flow metering section 34.

On the other hand, when angle α is an obtuse angle (an obtuse angle isnot shown except in FIG. 6), changing the location of a body shim from alocation between die body 12 and die body 16 to a location between diebody 16 and die body 14 can be advantageously used to decrease themetering gap of the transverse flow metering section. Conversely,reversing the location of a body shim when angle α is an obtuse angle,can be advantageously used to increase the metering gap of thetransverse flow metering section.

Thus, FIGS. 12 and 13 illustrate that for a second inventive embodiment,metering gap H is selectable by positioning metering faces 50, 52relative to one another. However, the relative positioning of meteringfaces 50,52 to one another is provided by Y-axis positioning. Asillustrated by the same centrally located position of body bolts 36 inclearance holes 39 in die body 16 in FIGS. 12 and 13, die body 16 ispositionable in a Y-axis direction without any Z-axis component to itsmovement.

In the first and second inventive embodiments, the exit channel maygenerally extend along the Z-axis, and fluid flow through the exitchannel may generally be in a forward Z-axis direction. In FIGS. 12 and13, the exit channel is formed in part by curved walls 44,46 of diebodies 12,14, respectively. In the slot die of FIG. 12, curved walls44,46 begin relatively closer to transverse flow metering section 34,whereas in the slot die of FIG. 13, the beginning of exit channel 42 isformed by generally planar walls 18,22, which transition to curved walls44,46 at a location relatively further from transverse flow meteringsection 34. However, the present invention is not necessarily limited tothe use of an exit channel that extends generally along the Z-axis. Theexit channel may, to the contrary, be oriented as desired orappropriate.

In the first and second inventive embodiments, body assembly bolts 36may extend through die body 12 and intermediately disposed die body 16and be anchored in die body 14, and may beneficially be in axialalignment with the Y-axis of the X-Y-Z coordinate system. Y-axisalignment benefits functionality.

The first and second embodiments of the invention are not mutuallyexclusive. To the contrary, the second inventive embodiment may alsoutilize Z-axis positioning, and the first inventive embodiment may alsoutilize Y-axis positioning. For example, with reference again to FIGS.12 and 13, die body 16 may be beneficially provided with a plurality ofbody bolt clearance holes 39 (only one shown in FIGS. 12 and 13), andbody shim 90 of the slot die of FIG. 12 may advantageously include aplurality of body bolt clearance holes 38 (only one shown),appropriately sized to provide clearance for Z-axis positioning of diebody 16 and/or die body 14, and for Z-axis movement of body shim 90.Beneficially, a backing structure as described in connection with afirst embodiment of the invention, with or without shims or the like asappropriate, may be used in connection with Z-axis positioning.

To move body shim 90 consistent with Z-axis positioning of die body 16,alignment pins or fasteners that extend through the body shim may beused. In this regard, reference is made to the description of FIG. 5when body shim 90 is located between die body 12 and die body 16, asillustrated in FIG. 12. When body shim 90′ is located between die body16 and die body 14 as illustrated in FIG. 13, the body shim 90′ may besecured to die body 14 using a plurality of fasteners 95 (only oneshown) having heads 96 (only one shown) that extend into a plurality ofclearance apertures 97 (only one shown) in die body 16. Beneficially,clearance apertures 97 are appropriately sized to provide for Z-axismovement of die body 16 if so desired, without interference from thefastener heads. The fasteners extend through a plurality of apertures 98(only one shown) in the body shim and are threaded into die body 14.

Similarly, when slot die 10 includes body shim 90, a Z-axis positionabledie body of a first embodiment of the invention may also be providedwith Y-axis positioning. Y-axis positioning may be accomplished withoutchanging the lip gap, by changing a body shim from a location betweendie body 12 and positionable die body 16 to a location betweenpositionable die body 16 and die body 14.

Two body shims of relatively less thickness but together ofsubstantially the same thickness as body shim 90, may be used, with onebody shim being located between die bodies 12,16, and the second bodyshim being located between die bodies 14,16. In this way, the transverseflow metering gap may have a relatively smaller change, and the lip gapis not changed. If a change to the lip gap were desired, the combinedbody shim thickness could exceed the thickness of shim 90. Othervariations within the scope of the present invention, will becomeapparent to one skilled in the art.

Advantageously, in the inventive technology, adjustment of thetransverse flow metering gap may be obtained independent of changingother flow channel metering gaps. In slot die casting or coatingprocesses, adjustment of the transverse flow metering gap withoutchanging or otherwise altering the lip gap can be beneficial ornecessary to accommodate process changes such as different flow rates,different fluid viscosities, and different process objectives.Beneficially, the inventive slot die allows selecting a different lipgap by the use of body shims or otherwise, without changing thetransverse flow metering gap. Advantageously, the inventive slot dieallows selecting a different exit orifice width or dividing anoutflowing stream into two or more flow streams by the use of deckleshims, without changing the transverse flow metering gap.

Various modifications and combinations have been described. The presentinvention may be carried out with other modifications and/orcombinations without departing from the spirit or essential attributesthereof. Accordingly, reference should be made to the appended claims asindicating the scope of the invention.

1. A slot die comprising a flow passageway that comprises a transverseflow-providing manifold, a flow metering section that provides atransverse flow metering gap and that is in fluid communication withsaid transverse flow-providing manifold and with an exit channel thatleads to an exit orifice that provides a final gap of the flowpassageway; and comprising a first die body, a second die body having ametering face, and a third die body having an opposing metering face, aplurality of body assembly fasteners, and a body shim suitably disposedin contact with said second die body; wherein said second die body isnormally non-adjustable wherein the opposing metering faces of saidsecond die body and said third die body form said transverse flowmetering gap, but when positionable, said second die body has an axis ofmovement that defines a Y-axis of an X-Y-Z coordinate system, and saidtransverse flow metering gap is thereby changeable independent of changeto the exit orifice gap by movement of said positionable second die bodyalong said Y-axis.
 2. The slot die of claim 1, wherein said plurality ofbody assembly fasteners are in axial alignment with said Y-axis of saidX-Y-Z coordinate system.
 3. The slot die of claim 1, wherein said exitchannel extends generally along said Z-axis.
 4. The slot die comprisinga flow passageway that comprises a transverse flow-providing manifold,flow metering section that provides a transverse flow metering gap andthat is in fluid communication with said transverse flow-providingmanifold and with an exit channel that leads to an exit orifice thatprovides a final gap of the flow passageway; and comprising a first diebody, a second die body having a metering face, a third die body havingan opposing metering face, a plurality of body assembly fasteners, and abody shim suitably disposed in contact with said second die body;wherein said die body is normally non-adjustable wherein the opposingmetering faces of said second die body and said third die body form saidflow metering section, but when positionable, said second die body hasan axis of movement that defines a Y-axis of an X-Y-Z coordinate system,and thereby said transverse flow metering gap is changeble by movementof said positionable second die body along said Y-axis, wherein saidmovement of said second die body along said Y-axis is effected by changeof a body shim location from a first position in contact with said firstdie body to a second position in contact with said third die body, orfrom said second position to said first position.
 5. The slot die ofclaim 1, wherein said flow metering section comprises a primary meteringstage, and a secondary metering stage that provides a relatively largertransverse flow metering gap than said primary metering stage.
 6. Theslot die of claim 1, wherein said flow metering section is disposed atan angle α selected from an acute angle and an obtuse angle, relative tosaid Z-axis.
 7. The slot die of claim 1, wherein said body shim is alsodisposed in contact with a die body selected from said first die bodyand said third die body.
 8. The slot die of claim 1, further comprisinga deckle shim disposed generally perpendicular to said Y-axis, and incontact with said first die body, and comprising at least one leg thatextends to said exit orifice.
 9. The slot die of claim 1, wherein saidplurality of body assembly fasteners secure said first die body, saidsecond die body and said third die body together in the normalnonadjustable condition.
 10. The slot die of claim 1, wherein saidplurality of body assembly fasteners extend through said second diebody.
 11. The slot die of claim 1, wherein said body shim is disposedbetween said second die body and a die body selected from said first diebody and said third die body.
 12. The slot die of claim 1, wherein saidexit channel is bounded by opposing surfaces of said first die body andsaid third die body.
 13. The slot die of claim 4, wherein said pluralityof body assembly fasteners are in axial alignment with said Y-axis ofsaid X-Y-Z coordinate system.
 14. The slot die of claim 4, wherein saidexit channel extends generally along said Z-axis.
 15. The slot die ofclaim 4, wherein said flow metering section comprises a primary meteringstage, and a secondary metering stage that provides a relatively largertransverse flow metering gap than said primary metering stage.
 16. Theslot die of claim 4, wherein said flow metering section is disposed atan angel α selected from an acute angle and an obtuse angle, relative tosaid Z-axis.
 17. The slot die of claim 4, wherein said plurality of bodyassembly fasteners secure said first die body, said second die body andsaid third die body together in the normal nonadjustable condition. 18.The slot die of claim 4, wherein said plurality of body assemblyfasteners extend through said second die body.
 19. The slot die of claim4, wherein the body shim located in said first position is a first bodyshim and the body shim located in said second position is a second bodyshim.
 20. The slot die of claim 19, wherein said first body shim andsaid second body shim are the same thickness.